-- This is the sixth and final installment in a series of stories, a refresher course of sorts, examining Auburn's defense and its adjustments to a changing game on offense --

AUBURN, Alabama -- The search for the next Richard Sherman, or Patrick Peterson, is in full swing at the NFL level.

Both Sherman and Peterson represent the NFL's new wave of cornerbacks, players who stand taller than 6-feet and have the change of direction skills to play on the edge. In the NFL Draft earlier this month, nine of the first 17 cornerbacks selected were taller than 6 feet.

Auburn is no different. Matching up with the rising passing numbers and no-huddle offenses popping up around college football requires a secondary with the length to disrupt the ball and the size to play the run.

"One of the other things we put a huge premium on in trying to recruit is length," Auburn defensive coordinator Ellis Johnson said. "Not just height but arm span, those type of things, because so much is done now in pass coverage and blitzing and other things where arm length and overall length is such a big factor."

Every one of the Tigers' six defensive back signees in the 2014 recruiting class is listed at taller than 6-feet.

In the NFL, the trend is somewhat based on the model set by the Seattle Seahawks, whose defense is built around a tall, rangy secondary. At Auburn, it's partly the preference of cornerbacks coach Melvin Smith, and partly the necessity of the game.

The advantage of recruiting that kind of height is obvious. Against a shorter secondary like the one Auburn fielded last season, teams have an advantage by putting the ball in the air where only the receiver can get it. In addition, shorter defensive backs have trouble packing on the pounds to be effective against the run.

But there's a catch. Not only does a player have to be tall and rangy these days, he still has to have the quickness of a smaller player. In the past, a 225-pound, 230-pound safety could spend all his time in the box.

Offenses don't offer that luxury anymore. Now, a player like signee Derrick Moncrief, the 6-2, 220-pounder who may start at the boundary safety, has to be solid in coverage to see the field.

"The old big strong safeties that used to come up and hit and run force and only had to cover a short zone, there's nowhere to put them anymore," Johnson said.

When he developed the 4-2-5 defense, Johnson added a "Star" position, a hybrid safety/linebacker who operates in both roles. Tigers' starter Robenson Therezie works with the safeties, but his position really requires its own set of skills.

The rest of Auburn's secondary has to be able to play multiple positions.

Versatility matters as much in the secondary as it does on the defensive line or at linebacker. For example, when the Tigers were thin at safety last August, Johnson moved Josh Holsey, a natural corner, into the spot at boundary safety.

Then, when Holsey was lost for the season due to injury, Johnson turned to another corner, Ryan White, to play a new position the rest of the season as the Tigers' dime safety.

"All those other guys (signed in the 2014 class) could probably play safety or corner, especially with the philosophy of our secondary," Johnson said.

Within the four traditional members of the secondary, though, Auburn is looking for specific physical traits.

On the boundary -- the short side of the field, and frequently the strong side of the offense's formation -- players have to be better suited to stopping the run. On the wide side, or the field side, the Tigers' defensive backs have to bring the kind of speed that can cover more ground.

As the Tigers stockpile defensive backs taller than 6 feet, the difference between the two comes down to body type and style of play.

"What we do with our boundary safety and our boundary corner, you've got to be a big, physical guy to play those two spots," Johnson said. "Then at the free safety and the field corner, you can be a little more athletic and maybe not quite as big."

Either way, expect Auburn's incoming defensive backs to look a little taller than they have in the past.